* Resolution: You say you bought a Macbook Pro but say the resolution of the built-in display is limited to 1280x800. This would imply that you have in fact bought a regular Macbook, not the Pro model. However, the £1400 you mention will indeed buy a base model 15" Macbook Pro. The 15" Macbook Pro runs at 1440x900 resolution, not 1280x800; this suggests that you are for some reason not running the machine in the correct native resolution, which will lead to relatively poor display quality due to scaling.
* A note on resolution: You are constrained by the LCD panel resolution of the hardware itself. The vast majority of all laptops are sold with 16:10 screens these days. If you really do have a MacBook Pro then it includes a dual-link DVI connector for an external monitor. You can drive up to 2560x1920 pixels (e.g. a giant 30" Dell or Apple LCD monitor) at 32bpp using a dul-link DVI cable, or over DisplayPort, if you're on the very-very-new MacBook Pro with the black keys. You have the usual range of display options for arranging the built-in LCD vs external display, or only using one of them, with the laptop switching automatically when the display is attached or detached (just as Windows can).
* Dock: The Dock can be made to auto-hide so you only see it when you move the mouse pointer to the bottom (or left, or right) edge of the screen. Go to the Apple menu, Dock -> Turn Hiding On, or do it via the Dock panel in System Preferences, or by the pop-up Dock context menu (right-click on an unused bit of dock - the separator between the applications and TinyDir-style file icons is a popular choice).
* American English is not mandatory There's an annoying tap-dancing to get the system and dictionary set to UK English; this is stupid for a UK-sold computer, but that's the way it is. Go to System Preferences, the International panel, and the Language tab. There's a list of languages on the left. Click on "Edit List..." and tick the "British English" option to add it to the list, if it isn't already (whether or not this is set up depends upon choices you made when you first booted the computer and got taken through the first-time setup screens). Click on "OK" to save your edited list. Back in the Language tab of the International settings pane, make sure that British English is dragged to the top of the list, if it is not already. For extra credit: Go to the Formats tab and make sure that "United Kingdom" is set for the formats menu too. With this done you'll have a UK-English system dictionary and grammar checker, although there are still a few missing "u"s in a few places, showing that not all Apple programmers are accessing the right dictionaries for their UI internationalisation. Ooops.
* The trackpad has two buttons or, if you're using the brand new black key Macbook Pro, lots, via gestures and so-on. The second button is accessed by tapping with two fingers rather than one and acts very like middle-click on RISC OS. I couldn't live without it. To avoid confusing people, Apple leave all multi-tap and multi-touch gestures turned *off* by default on any fresh operating system installation. Go to System Preferences, Keyboard & Mouse, Trackpad tab. I generally leave the single-tap button stuff off and use the 'real' hardware button else I find I end up accidentally "clicking" when I don't mean to; but the two-finger right-click style tap is almost impossible to do by accident. Tick "Tap trackpad using two fingers for secondary click" if using a previous generation laptop, else follow the various hints, animations, guides and videos embedded in the whizzy new trackpad configuration tab for full gestural multi-touch goodness.
* Copy and paste: The non-persistent selection model of Mac OS is hardly unique; indeed RISC OS is one of the very few operating systems that does it that way, with newer versions adding in transient selection clipboard based schemes too. Now that you know you have a right-button in the trackpad (the two-finger click) you can get a menu up to do copy and paste, but I'm not sure how that's better than using the keyboard shortcuts. The built-in clipboard does not expose a history; that is, it only "remembers" the most recent thing you copied or cut to it. Have a look at "[link]" for a free way to get at a clipboard history, if you find that kind of thing useful.
* Drag and drop: I just loaded Keynote. I dragged the JumpCut icon from that page mentioned above in Safari to a blank bit of the Keynote presentation. It got added to the presentation. I'm not sure why you had trouble here; perhaps you were accidentally selecting text or something first, or perhaps you dragged the picture into one of the text frames (in which case, the associated alternative text that goes with the picture is inserted into the text). So don't try and over-complicate it with selections or copying or pasting or whatever - just drag the picture from Safari to Keynote and It Just Works. Ahem
* Note that you can drag pictures from Safari to Finder windows or the Desktop to save them. Like most such filename-less operations, the filename will be automatically chosen to avoid overwriting anything that's already there.
I had similar feelings about RISC OS after using and getting to properly know Mac OS 10.4, in terms of it being simultaneously enlightening and depressing. When using Windows, it's just a mess in every respect. Linux doesn't do a fair few things the way I'd have done them, probably because its open nature means there are loads of competing frameworks and libraries to do things. The choice is great, but applications lack integration as a result; just look at KDE vs Gnome, the lack of system-wide spell checkers for all applications or the number of different sound systems that are available. OS X's frameworks, on the other hand, coupled with the way the OS has evolved over its various versions (if you want to learn about the guts: Singh's "Mac OS X Internals" is huge, but excellent) are very logically structured and generally well put together, if far from perfect. At a macroscopic scale, the software's clean architectural vision is very evident, whatever you might think about smaller scale issues such as the layers of legacy APIs in the Mach kernel. Had the time, money and manpower been available, I suspect RISC OS would have eventually done many things in the same way.